Son of Nudd and brother of Gwyn ap Nudd, little is said of Edern outside of "Gereint a Enid" in the Mabinogion, and his later incarnation as Sir Yder in French Arthurian romance.

In "Gereint," Edern is the Sparrow-Hawk Knight whom Gereint must battle in order to free Enid's father's dukedom. In one legend, he was a knight of Arthur's court who was sent to fight three giants and died because Arthur was late to the battle. Another legend says that he was a bard who became a monk. Sadly, the truth of his godhood is obscured by diverging legends.

In French romance, it is said that Yder was one of the lovers of Queen Guenevere,[1] and that he killed a bear that entered her chamber while she slept. As "Arthur" means "bear"... Hmm.

[1.] Guenevere is credited with a number of lovers, not just Lancelot--Kay, Gawain, Yder, Mordred, Lanval, and many others. Well, it's said Arthur had a number of mistresses, so fair's fair.